Exception wrapping system

ABSTRACT

The described technology is directed towards handling errors in an application program that allows for a taxonomy and precedence order of errors. Exception wrapping includes preserving relevant information with an exception, and consolidates a series of errors into a single dominant exception instance that is handled appropriately depending on the exception type. Also described is a centralized exception manager that outputs an interactive dialog based upon the exception type, and takes a recovery action based upon user interaction with the dialog.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. patent applicationSer. No. 14/805,087, filed Jul. 21, 2015, which claims priority to U.S.provisional patent application Ser. No. 62/028,378, filed Jul. 24, 2014.The entireties of these applications are incorporated by referenceherein.

BACKGROUND

Encountering a series of errors (failures) is common in computer programcode. A series of errors may occur when some original error leads tosubsequent failures. This can occur in synchronous code if the originalerror is caught and re-thrown. This can also occur in asynchronous codeif an asynchronous routine fails and thus causes handlers hooked intothat asynchronous routine's completion to fail as well.

Many programming languages like JavaScript® provide some built-infunctionality for error handling. For example, JavaScript® provides theError type and try and catch statements, which facilitate the throwingof an Error instance. While very useful in many instances, with acomplex series of errors the built-in error handling functionality isoften insufficient for diagnosing a problem and surfacing it correctlyto the end user.

For example, if one function call fails (due to a bug or exceptionalcondition), then a series of functions and components may fail. It isoften not clear which failure in this chain of failures should takeprecedence and be shown to the end user. Additionally, the initial errorthat caused the series of errors and the asynchronous call graph(failure chain/graph) can be difficult to determine.

SUMMARY

This Summary is provided to introduce a selection of representativeconcepts in a simplified form that are further described below in theDetailed Description. This Summary is not intended to identify keyfeatures or essential features of the claimed subject matter, nor is itintended to be used in any way that would limit the scope of the claimedsubject matter.

Briefly, the technology described herein provides a mechanism ofdetermining error precedence and of preserving contextual data capturedfor each failure, including each failure in a chain of failures. Forexample, an error may be explicitly thrown by application program code(e.g. due to unexpected state), an error may arise from a function callto an external component, or an error may be generated by the runtime(e.g. due to a code bug).

An exception wrapping system as described herein presents an extensibleException type that can wrap the thrown error to capture additionalrun-time context. The exception wrapping system also provides a derivedexception type hierarchy that can be used to determine precedence for achain of wrapped exception instances. The resulting highest-precedenceexception instance may be routed to an exception manager, whichdetermines how to handle the resulting exception, which may include whatto display to the user (e.g., an interactive dialog that is relevant tothe error) and optionally what recovery action or actions to take.

Other advantages may become apparent from the following detaileddescription when taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The technology described herein is illustrated by way of example and notlimited in the accompanying figures in which like reference numeralsindicate similar elements and in which:

FIG. 1 is an example block diagram of various example components forimplementing a wrapped exception handling system according to one ormore example implementations.

FIG. 2 is a representation of an example hierarchy of derived exceptiontypes, according to one or more example implementations.

FIG. 3 is block diagram and data flow diagram representing how an errorcauses an exception to propagate through a wrapped exception handlingsystem, according to one or more example implementations.

FIG. 4 is a representation of an example generalized dialog template,according to one or more example implementations.

FIGS. 5-8 are representations of example information related to anexception type that may appear in a dialog, according to one or moreexample implementations.

FIG. 9 is a flow diagram showing example steps related to determining anexception instance type based upon the most-derived applicable exceptiontype in a hierarchy, according to one or more example implementations.

FIG. 10 is a flow diagram showing example steps related to handling anexception instance type inside of an exception manager, according to oneor more example implementations.

FIG. 11 is a block diagram representing an example computing environmentinto which aspects of the subject matter described herein may beincorporated.

DETAILED DESCRIPTION

Various aspects of the technology described herein are generallydirected towards a wrapped exception handling technology, including anarchitecture for handling program errors that allows for a taxonomy andprecedence order of errors. In general, a captured error is wrapped asan exception instance with contextual information relevant to the error.In one or more implementations, the wrapped information is maintained inproperties of an Exception object instance. An exception manager obtainsthe exception, e.g., the Exception object instance and its information.The exception manager is able to provide a dialog to the user regardingthe type of error, which forces the user to interact with that dialogand choose a recovery action in order to continue using the program.

As will be understood, one or more aspects of the wrapped exceptionhandling technology are directed to trying to surface the most relevanterror when a series of errors is encountered. Exception wrapping asdescribed herein is able to consolidate the series of errors into asingle dominant exception instance that can be handled appropriately,depending on the exception.

It should be understood that any of the examples herein arenon-limiting. For instance, some of the examples are based uponJavaScript®, however these are only examples, and the technologydescribed herein may be used with other programming languages. Asanother example, some of the error examples are directed towards a videostreaming application program and its associated service providers,however the technology applies to any computer program. Still further,an entertainment/game console is one example computing environment,however any other suitable computer-based device such as a personalcomputer, tablet device, mobile computer device and the like mayimplement the technology described herein. As such, the technologydescribed herein is not limited to any particular embodiments, aspects,concepts, structures, functionalities or examples described herein.Rather, any of the embodiments, aspects, concepts, structures,functionalities or examples described herein are non-limiting, and thetechnology may be used in various ways that provide benefits andadvantages in computing and error handling in general.

FIG. 1 is a generalized block diagram showing example aspects of thetechnology described herein. In general, program code includes a routine102 or the like that throws an error 104 under some condition. Asdescribed above, as some non-limiting examples of errors, an error maybe explicitly thrown by application program code (e.g. due to unexpectedstate), an error may arise from a function call to an externalcomponent, or an error may be generated by the runtime (e.g. due to acode bug). An error processing component, referred to herein as wrappingcode 108, receives the error and processes it as described herein. Inthe exemplified implementation, this typically includes having the error104 wrapped into an exception instance 110 and ultimately sent to anexception manager, e.g., a centralized exception manager.

To this end, as described herein, the wrapping code 108 (e.g., alsogenerally referred to as Exception.wrap) wraps the error with relevantinformation, and outputs a wrapped exception 110. In one or moreimplementations, the wrapped exception 110 is in the form of anException object instance having properties that contain relevantinformation regarding the error. The wrapping code 108 (or othersuitable component) optionally may output exception-related informationas a log entry 112 or the like, e.g., an entry indicating that anexception instance was encountered, for debugging or other analysispurposes. For example, the resulting wrapped exception instance that isreturned from Exception.wrap( ) normally contains contextual data aboutthe series of failures that is sufficient to be able to diagnose theoriginal issue and also reconstruct the failure chain/graph.

The wrapped exception 110 is (typically) routed to an exception manager114. Among its operations, the exception manager 114 accesses a table ofhandlers 116, in which each handler comprises a mapping between anexception type and a corresponding dialog; (in FIG. 1 the exemplifieddialog 118 includes one or more recovery actions). The exception manager114 thereby outputs a corresponding dialog 118 to the user, whichincludes one or more recovery actions 120. An example of one suitableexception type table is shown below.

The dialog 118 also resumes the program at an appropriate locationdepending on the type of exception and (typically) the user input to thedialog 118. Note that in one or more implementations, user input may beneeded, even for a default recovery action; a reasonable default choiceof recovery action is restarting the application, which is likely thesafest/most likely to succeed recovery action if a more isolatedrecovery action cannot be determined. However in other implementations,there may not be a handler/dialog mapping for one or more of theexception types, in which event the exception manager 112 (if such anexception is not otherwise already handled) along with the correspondinghander for that exception takes an appropriate default recovery actionwithout user input.

With respect to one or more example implementations, as used herein, a“base” Exception type is a type definition that includes functionalityfor the wrapped exception handling system. As a generic base type, thebase Exception type does not define specific errors or errorprecedence—derived exception types are used for this purpose (e.g.,derived in the sense of OOP [Object-Oriented Programming] inheritance).In one or more implementations, a base Exception type needs to beincluded in the root namespace or module so it can be used system-wide.

In one or more implementations, the base Exception type includes thefollowing attributes:

-   -   ID: a UUID (universally unique identifier)    -   Message: an internal developer message to diagnose the cause of        the Exception    -   Callstack: the function execution stack at the time the        Exception instance is created    -   Area: (optional) the area in the program where the exception        occurred; often provides more specific guidance than Callstack.    -   Contextual Data: (optional) arbitrary data that may help in        debugging, e.g., values of variables at the time of the        exception, property values and so on.

The Exception type may derive from a built-in error type definition inthe target programming language if one exists and can be derivedtherefrom. For example, in JavaScript® the Exception type derives fromthe built-in JavaScript® Error type. Note that the Message property inthe Exception type maps to the JavaScript® Error message, and Callstackalso is part of JavaScript®; (however, errors are not necessarily thrownby JavaScript® and instead may be passed via some other mechanism, e.g.,a JavaScript® Promise rejection. Thus, without wrapping, Callstack isnot always provided; however via wrapping the Callstack property isprovided even if an error is not thrown). Deriving from the built-inError type definition allows built-in machinery in the language runtimeto treat Exception object instances as native error instances (so, forexample, they can be caught and thrown). For example, in FIG. 3, programcode that creates an object may use “try” and “catch” statements tothrow an Exception object instance using built-in JavaScript®functionality. Similarly, a dispatcher 331 may throw an error via “try”and “catch” statements:

routine( ) { // async dispatcher loop through work items - e.g., perframe loop  try {   // run work item (i.e. the program code routine 102in FIG. 1)   ...;   ...;  }  catch (reason) {    var e =Exception.wrap(reason, {     message: “example message”,     area:“example area”});    ExceptionManager.handle(e);  } }

An exception also may be created if an asynchronous callback fails. Forexample, if a JavaScript® Promise fails, the failure may be transformedinto an exception instance using wrapping code that captures theCallstack and other information. From there, in one or moreimplementations, the exception manager 114 maps exception instance typesto error dialogs/pages, and does not ignore or pass on errors; (howeverin alternative implementations, an exception manager may choose toignore an exception, throw a different exception, pass the exception onto another entity, and so forth). Note that, for example, the exceptionmanager may use the asynchronous dispatcher for dispatching itsasynchronous work items, and thus handling the error in the exceptionmanager instead of halting the asynchronous dispatcher allows theexception manager to continue operating to provide the user dialog, andthe like.

Moreover, in one or more implementations, the design is such that thedecision to ignore an error typically does not occur in the exceptionmanager, because the exception manager is the final destination forunhandled errors. Instead, failures eventually are routed to theexception manager unless they are explicitly caught and ignored (e.g.,by a “catch” statement or Promise rejection handler). For example,sometimes expected but non-critical failures are caught and ignored. Asa more particular example, if an image fails to load, the system wantsto catch that failure earlier, instead of letting it bubble/route to theexception manager. If allowed to route to the exception manager, withouta plan for ignoring it at the exception manager, the failure may causeproblems, e.g., if loading the image was part of some larger work itemsuch as loading the page, the larger work item gets aborted as soon asthe error is thrown. Therefore, the system is designed to catch andignore expected errors, rather than relying on the exception manager toignore such errors.

Derived exception types are used to specify the nature of specificexceptions. Derived exception types are type definitions that derivefrom the Exception base type and can form their own type hierarchies. Ingeneral, the exception wrapping system gives precedence to a morederived type over a base one, as each level in the hierarchy providesmore specific information.

By way of example, as generally represented in the hierarchy (taxonomy)of FIG. 2, ServiceException 220 may derive from NetworkException 224which in turn derives from the Exception base type (e.g., Exception222), and AuthenticationException 226 and ContentUnavailableException228 may each derive from the ServiceException 220 type. TheContentUnavailableException 228 indicates a more specific nature offailure, e.g. that a particular requested asset (e.g. a video instance)is not available on the server, within the class of ServiceExceptions.This more specific type allows the exception manager 114 (FIG. 1) toprovide a more specific dialog to the user, as well as provides moreinformation for use in debugging, analytics, and logging.

Derived exception types can be included in sub-namespaces or modulesdepending on the nature of the exception type. For example,ServiceException can be included in a dataservices namespace and modulebecause it is only originated in data service code.

In one or more implementations, the exception manager 114 is a centralhandling mechanism for different exception types. Exceptions get routedto the exception manager 114, such as via a global error handler 330(FIG. 3). Note that in applications (e.g., in JavaScript® or other) itis often possible to register a global (central) error handler, which isa central hook to catch and handle unhandled errors in the application.For this system, a global error handler 330 is added to the application(or “process”) that calls Exception.wrap(e) (for an unhandled error “e”)and sends the result to the exception manager 114.

In such an implementation, the exception manager 114 may implement asingleton pattern because only one exception manager instance is neededin the running application. The exception manager 114 may include a hookto which exceptions can be passed for handling and a mapping ofexception types to handlers. Because exception types may be declaredacross different modules, the exception manager 114 may be defined on atop layer that sits above these other modules.

The exception manager 114 maps different exception types to handlers116. Generally, each handler results in showing information (e.g. byshowing a message dialog) to the user indicating the nature of theexception and provides an interactive input mechanism, such as one ormore buttons with paired recovery actions. In the event that a baseException object instance or native error occurs that was never wrappedin a derived exception type, the base Exception type/native error mapsto a generic exception dialog that is then used.

The wrapping code 108 and exception manager 114 thus handle exceptions,including preventing (to a high probability) the possibility of anyunhandled error crashing the application. The exception manager 114 alsohandles and ignores new incoming exceptions while exception informationis currently being shown to the user and before the user has selected arecovery action.

Exception dialogs are modal message dialogs describing the nature of aspecific exception type, as generally represented in the general exampledialog template 444 of FIG. 4; (note however that exception dialogs arejust one option for handling exceptions in the exception manager). Inone or more implementations, each dialog includes a title 446, message447, and set of buttons 448, 449 each with a paired recovery action(there is typically at least one button with a paired recovery action).In this example, exception dialogs are not dismissible except throughsuch a button—the user has no other way of closing the exception dialog,e.g., there is no close button and no light-dismiss capability, wherebythe user is forced to acknowledge the exception and take a recoveryaction by clicking on a button.

The following exception type table is one example of how each exceptiontype, dialog, button and action may be associated with one another for avideo streaming application program:

Exception Exception Exception Exception Dialog Dialog Type Dialog TitleMessage Buttons Description Activation “Activation “Activation failed.“Ok”: Navigate Unexpected bad Exception Error” Please try again later.”back response from activation service Authentication “Authentication“There was a problem “Retry”: Retry Login failure Exception Error” withHBO GO ® login authentication. Please “Reactivate”: try again. If theproblem Navigate to persists, try reactivating activation your Consolefor HBO page GO ®.” ContentUnavailableException “Content “The requesteditem is “Ok”: Navigate Item out of catalog Unavailable” no longeravailable.” back NetworkException “Network Error” “Please try again in a“Restart” Generic network few minutes. HBO (or “Ok”): request failureGO ® will now restart.” Restart app PlaybackException “Video Error”“We're having trouble “Go Back” Error starting playing this video right(or “Ok”): video or during now.” Navigate back video streamingPinException “Pinning Error” “The pin operation “Ok”: Dismiss XBOX pinsystem could not be the dialog API failure completed.” Reactivation“Reactivation “Your activation “Ok”: Navigate Authentication RequiredRequired” information is no longer to activation service indicatesException valid. Your Xbox One page reactivation is must bereactivated.” required or authentication succeeds but no activationrecords are found ServiceException, “Service Error” “Please try again ina “Ok”: Restart HBO service ServiceError few minutes. HBO app returnedinvalid or CodeException GO ® will now restart.” no response Exception“Error” “An application error “Ok”: Restart Generic dialog for hasoccurred. HBO app unexpected app GO ® will now restart.” error (e.g.code bug) ActivationTimeout “Activation “Activation timed out “Ok”:Dismiss Activation timeout Exception Timeout” due to lack of activity.dialog and Please try again.” refresh activation page with new codeGOSTException “Too Many “You have exceeded “Ok”: Navigate SimultaneousDevices in Use” the maximum number back stream limit of simultaneousexceeded devices for your HBO GO ® account. To use HBO GO ® on your XboxOne, please stop watching HBO GO ® on one of the other devices currentlyin use.” “ContentRestricted “Content “Access to this content “Ok”:Navigate Attempt to play Exception” Locked” is locked due to your backcontent restricted {AFFILIATE} by affiliate. account's Parental Controlssettings. Check your {AFFILIATE} settings or contact {AFFILIATE} formore information.”

FIG. 5 (ActivationException) and FIG. 6 (AuthenticationException) showhow the title 546, 646, description 547, 647 and button fields 548, 648and 649 may be rendered based upon this table for the first twoexceptions listed therein. Note that FIGS. 5 and 6 (and similarly FIGS.7 and 8) are merely for purposes of illustration, and are not intendedto be accurate representations of actual dialogs.

For exceptions deemed severe (e.g., a NetworkException indicating thatinternet connection has been disrupted as in FIG. 7), the exceptionmanager may define only one recovery action that restarts theapplication and pair this with a button 748 showing “Restart” text. Forexceptions deemed less severe (e.g. PlaybackException), the exceptionmanager may define only one recovery action that simply navigates backto the previous page and pairs this with a button 848 (FIG. 8) showing“Go Back” text.

Exception wrapping is a mechanism that enforces exception precedence andtransforms a series of errors into a single exception instance thateventually gets passed to the exception manager for handling. By way ofexample, in a series of errors, consider the initial point of failure(e.g., error “origination”). This may be a native error thrownexplicitly by a developer's code, an error generated by the languageruntime when it encounters problematic code, or an exception instance ofany derived exception type or the base Exception type that is createdand thrown explicitly. Note that this list is not exhaustive, e.g., anerror may be thrown by an included library's code, or an error may becaused by an unhandled JavaScript® Promise rejection as other examples.

A series of errors may occur when the original (origination) error leadsto subsequent failures. This can occur in synchronous code if theoriginal error is caught and re-thrown. This can also occur inasynchronous code if an asynchronous routine fails and thus causeshandlers hooked into that asynchronous routine's completion to fail aswell.

In the synchronous case, when the original error is caught it can bewrapped before it is re-thrown. Wrapping allows optionally modifying theexception properties and type before it is re-thrown.

In the asynchronous case, the original asynchronous routine indicates itfailed and optionally may provide the Error instance that caused it tofail. The code that hooked that asynchronous routine has the opportunityto wrap the optional Error instance in an exception or create a newexception if no Error instance was provided. Thus, exception instancescan be wrapped at each link in an asynchronous callback chain.

Note that there is a difference between the first asynchronous routinein a chain and the asynchronous routine that originates the error. Byway of example, consider the following chain of asynchronous tasks: A->B ->C. Async task “A” calls into async task “B” as part of its work,which calls into async task “C”. The tasks start in the order A, B, C.Task “C” originates a failure and its rejection handler gets called withthat failure (e.g., an Error instance). The rejection handler for task“C” wraps the failure reason as an exception and then rejects task “B”with the wrapped exception instance (because “C” is a required subtaskof “B,” and “C” failed). Then, the rejection handler for task “B” wrapsthe failure again with different data (type, message, area) and thenrejects “A” with this wrapped exception instance (because “B” is arequired subtask of “A”).

In one or more implementations, the combination of the exception typehierarchy and the wrapping behavior creates a precedence order forexceptions and transforms a series of exceptions into one dominantexception instance. By way of example, consider an object being builtthat represents the current user's metadata. In this example, the objectis created asynchronously because it makes some service calls to fetchdata, so it makes an asynchronous callback when creation is complete.Thus, for example, the user object needs to make an authenticatedservice request to pull user metadata. If the service request fails itwill originate a ServiceException instance. Then, the authenticationroutine that made the service request calls AuthenticationException.wrap(e), where ‘e’ is the object returned from the failingasynchronous service request callback (in this case ‘e’ represents aServiceException instance). If as in FIG. 2 the calling type(AuthenticationException) is not an ancestor type of the argument type(ServiceException), calling Authentication Exception.wrap(e) creates andreturns an instance of the calling type (AuthenticationException). Then,the authentication routine fails with the AuthenticationExceptioninstance. Finally, the object creation code is notified that anasynchronous callback failed with some error “e”, so the object creationcode calls Exception.wrap(e).

The object creation code does not know specifically which callbackfailed, so the object creation code calls the wrapping code with thegeneric base Exception type. In this case, ‘e’ represents anAuthenticationException instance, whereby calling Exception.wrap(e)preserves the AuthenticationException instance instead of returning anew base Exception object instance because the calling type (Exception)is an ancestor type of the argument type (AuthenticationException). Theobject creation code then invokes its failure callback with thepreserved AuthentationException instance returned from theException.wrap(e) call. Assuming there are no other asynchronouscallbacks, the AuthenticationException instance then propagates to theexception manager, which maps it to an appropriate error dialog to showthe user that authentication failed with a descriptive message and anappropriate recovery action. In this example, even though theAuthenticationException.wrap( ) call occurred in the middle of a chainof failures, the exception wrapping system preservedAuthenticationException as the dominant exception type due to theexception type hierarchy.

FIG. 3 shows example exception wrapping and propagation for the aboveexample. In FIG. 3, the flow is represented by the circled numerals,described below:

-   1. Object creation code 332 makes an asynchronous call to    authenticate.-   2. Authentication code 334 makes an asynchronous service call.-   3. Service Client code 336 sends an asynchronous request to a server    338 (e.g. via the HTTP protocol).-   4. Server 338 returns an error (e.g., “403: Forbidden”).-   5. Service call rejection handler in the Service Client 336 (e.g.,    invoked as a callback) originates the error ‘e’ using    ServiceException.new( ) which returns a new ServiceException    instance.-   6. Authentication rejection handler in the authentication code 334    wraps the ServiceException instance ‘e’ using Authentication    Exception.wrap(e), which returns a new AuthenticationException    instance because the calling type (AuthenticationException) is not    an ancestor type of the argument type (ServiceException).-   7. Object creation rejection handler in the object creation code 332    wraps the AuthenticationException instance ‘e’ using    Exception.wrap(e), which preserves the AuthenticationException    instance because the calling type (Exception) is an ancestor type of    the argument type (AuthenticationException). The unhandled rejection    callback for Object creation rejects with the    AuthenticationException instance.-   8. The Object creation rejection is not hooked by any parent task.    Therefore, the Object creation rejection is an unhandled rejection    and gets routed with its AuthenticationException instance to the    global error handler 330.-   9. The exception manager 114 maps the AuthenticationException to the    appropriate text and recovery action to show in an authentication    exception dialog (e.g., FIG. 6) and displays that dialog 318 to the    user.

Calling Exception.wrap( )as is done numerous times in FIG. 3 returns anexception instance and can take either a native error instance or anexception instance as its argument.

Further note that a Dispatcher node 331 (shown as a dashed block toindicate a different error from the object creation error) also callsException.wrap(e) for an error case. Async tasks on the Dispatcher 331are executed within a try/catch statement that catches errors and callsException.wrap(e) on the error (“e”) and then sends this wrappedexception to the exception manager 114. This allows the Dispatcher 331to quarantine the failing async call and to continue processingremaining async work items (to keep the application UI responsive andnot frozen) while the error is being handled by the exception manager114.

FIG. 9 represents general logic that may be implemented in theException.wrap( ) wrapping code, beginning at step 902 where a caughterror is passed. If a native error instance is passed (step 904), then anew exception instance is created from the native error instance (step906). If available, data from the native error instance is copied overto the new exception instance (e.g., message, callstack) at step 908instead of creating it from scratch.

If instead at step 904 an exception instance is passed, then either anew exception instance is created to supersede the passed exceptioninstance or the passed exception instance is preserved (depending onexception precedence as described herein, e.g., the hierarchy in FIG.2). In other words, the more specific level in the hierarchy thatapplies to (is known for) that exception instance is used.

More particularly, Exception.wrap( )uses the exception type information(step 910) to determine whether to supersede or preserve the originalexception instance when one is passed. Exception.wrap( ) is called withthe desired exception type based on the context in the code where theException.wrap( ) call is made. For example, in an authenticated servicerequest, a failing asynchronous service response is to be wrapped usingAuthenticationException.wrap( ) because an AuthenticationException isdesired here. When the calling type is not an ancestor type of thepassed exception instance type, then a new exception instance is createdof the calling type (step 912). Thus, callingAuthenticationException.wrap(serviceExceptionlnstance) returns a newAuthenticationException because AuthenticationException is not anancestor of service Exception Instance. In this exampleserviceExceptionInstancemay be of type ServiceException. BecauseAuthenticationException is not an ancestor of ServiceException,AuthenticationException.wrap(serviceExceptionInstance) creates anAuthenticationException that supersedes the passed base ServiceExceptioninstance. On the other hand, callingServiceException.wrap(authenticationExceptionInstance) preserves thepassed AuthenticationException instance because ServiceException is anancestor of AuthenticationException. Note that regardless of whether anew exception instance is created or not, any data of the calling typemay be copied and preserved at step 914. When creating a new instance,one alternative way to copy is to save the old instance as a property ofthe new instance and thereby preserve the prior data.

The Exception.wrap( ) logic generally may operate as in the examplebelow:

// part of Exception.wrap( ) determining whether new instance will becreated function wrap(TargetType, reason) {  if (reason instance ofTargetType);   return reason;  else   return TargetType.new(reason); }

Thus, if calling AuthenticationException.wrap( ) and the reason alreadyis an AuthenticationException, then no new instance is created. However,if calling AuthenticationException.wrap( ) and the reason refers tosomething higher (less specific) in the hierarchy, e.g.,ServiceException, then a new instance of an Authentication Exception iscreated.

Exception.wrap( ) also may log data regarding the exception to internallog handlers as represented by example step 916. Note that differentlogging mechanisms may be invoked depending on the path taken in FIG. 9,in which event different logging steps may exist in each path. When anException.wrap( ) is called with an exception instance parameter, thepassed exception instance's ID (at least) is preserved. Thus, to debugexceptions in the application, a developer can consult the exceptionlogs and trace the flow of an exception through the code using theexception instance's ID. The exception logs can be transmitted from theapplication to a log aggregation service, for example.

With respect to exception propagation, errors can occur anywhere withinan application and need to be funneled to the exception manager. Errorsthat occur while running work items may be caught by the dispatcher 331(FIG. 3) and routed to the exception manager 114. Global error handling330 exists to catch other errors because uncaught errors will likelycrash the application.

Errors caught by the dispatcher 331 or global error handler 330 arerouted to the exception manager 114 to show an appropriate exceptiondialog (although for errors that are ignored, the wrapping code may onlylog the error and handle it, that is, not re-throw or return it), andthe exception manager may not be invoked). For example, if theapplication is running in a web browser, then the browser's error hookneeds to be connected to the exception manager. In this case, theapplication process may hook the window.onerror event in one exampleimplementation. In one or more implementations, the global errorhandling is a last resort for unexpected errors and exceptions that arethrown synchronously. For errors in dispatched work items, the dispatchmechanism that runs work items catches errors thrown by work items andpasses them to the exception manager so as to allow other queued workitems to continue running uninterrupted. Exception instances may belogged when they are handled by the global exception manager.

FIG. 10 is a flow diagram showing example steps that may be taken by theexception manager, beginning at step 1002 where the exception managerreceives the exception instance type.

Step 1004 represents accessing the exception type table, with step 1006representing the outputting of the dialog associated with the type. Step1008 waits for user input, (e.g., asynchronously via an event or thelike rather than a loop as may be suggested in FIG. 10). Note that in ascenario in which an exception is able to reach the exception managerbut does not have an associated dialog, the exception manager may simplytake the default associated action, as represented by the dashed linefrom step 1004 to step 1014; however, in one or more implementations,there is a default dialog for this situation.

When input is received, step 1010 evaluates whether the user made adecision as to the type of action to be taken (e.g., there were multiplebuttons from which to select), or, as in many situations, there was onlyone action associated with the exception and only awaited useracknowledgement (e.g., there was only a single button). If the dialogcontains more than one possible action, step 1012 determines an actionmapped to the user decision. Step 1014 takes the action related to theexception, e.g., restarts the program or navigates to some appropriatelocation in the program.

As can be seen, the wrapped exception handling system allows a complexapplication with an asynchronous architecture to define a precedence ofexception types and provide centralized exception handling. Theexception precedence system benefits end users by ultimately showingappropriate exception dialogs depending on the nature and context of anapplication failure. Logging during exception wrapping and propagationhelps developers trace the origination and flow of exceptions in theircode to track and isolate the bugs that cause exceptions for end users.

Calling Exception.wrap( ) for each failure in a async chain of failureswith an appropriate type for the nature of the failure allows thecurrent routine's rejection handler to not have to consider the problemof determining failure precedence. This is beneficial becausedetermining failure precedence at the site where a failure occurs can bedifficult if not impossible because the current routine may either be aprimary task or a subtask, but the failure handling code for the currentroutine may not have enough context to decide which it is. Exceptionwrapping solves the precedence problem using the asynchronous call orderand type hierarchy.

One or more aspects are directed towards wrapping code coupled to anerror handler of a routine, in which the routine produces an error andthe wrapping code wraps the error with relevant information to provide awrapped exception instance. An exception type hierarchy is used topreserve information in the wrapped exception instance including anexception type An exception manager receives the wrapped exceptioninstance and determines one or more actions to take based upon theexception type of the wrapped exception instance. The wrapped exceptiontype may be derived from a higher-level exception type in the exceptiontype hierarchy.

The exception manager may take the one or more actions, including topresent an interactive dialog associated with the exception type. Tothis end, the exception manager may access an exception type table thatassociates exception types with dialogs to select the interactive dialogfor the exception type. The dialog may include an interactive inputmechanism, which when selected, results in the exception manager takingfurther action to restart a program that contains the routine, tonavigate to a location in a program that contains the routine, in whichthe location is determined based upon information in the wrappedexception type, to navigate back to a prior location or retry anoperation that caused the error.

Also described is an optional logging mechanism that logs datacorresponding to the wrapped exception instance.

The wrapping code may be configured to determine if the errorcorresponds to a native error, and if so, to create a new exceptioninstance and preserve at least some available data associated with thenative error, if any, in the new exception instance. The wrapping codemay be called with a calling exception type, and the wrapping code maydetermine if the calling exception type is an ancestor type of a passedexception instance type, and if so, to preserve the passed exceptioninstance as the wrapped exception instance, and if not, to create a newexception instance corresponding to the calling exception type. Thewrapping code may create a new exception instance type, and preserve atleast some data of the passed exception instance type in the newexception instance type.

One or more aspects are directed towards receiving a call related to aprogram error, in which the call is associated with a passed nativeerror instance or the call is associated with a passed exceptioninstance and a calling exception type. Described is determining if thecall corresponds to a passed exception instance, and if not, creating anew exception instance of the calling exception type to represent theprogram exception and preserving information corresponding to any dataof the passed native error instance in the new exception instance. Ifthe call corresponds to a passed exception instance, described isdetermining if the calling exception type is an ancestor type of thepassed exception instance type, and if not, creating a new instance ofthe calling exception type to represent the program exception, or if so,preserving the passed exception instance to represent the programexception.

When the calling exception type is not an ancestor type of the passedexception instance type, information corresponding to data of the passedexception instance may be preserved in the new exception instance.Preserving the information may include maintaining the passed exceptioninstance or at least some of the data of the passed exception instanceas at least one property of the new exception instance.

When the calling exception type is an ancestor type of the passedexception instance type, information corresponding to data of the passedexception instance may be preserved in the wrapped exception instancethat gets returned.

Data corresponding to the wrapped exception instance may be logged.

The exception instance may be received at an exception manager, whichmay output a dialog based upon the received exception instance type, andtake a recovery action based upon the received exception instance type.

One or more aspects are directed towards determining a wrapped exceptiontype based upon a hierarchy, including using a wrapped exception typethat applies to an error thrown while executing a program, rrouting thewrapped exception instance to an exception manager, determining a dialogand associated with the wrapped exception instance type, outputting thedialog and taking action based upon user interaction with the dialog.

Determining the exception instance type may include determining if acalling exception type is an ancestor type of a passed exceptioninstance type, and if so, preserving the passed exception instance asthe wrapped exception instance, and if not, creating a new exceptioninstance corresponding to the calling exception type. Taking the actionmay include restarting the program, navigating to a location in theprogram, navigating back to a prior location, or retrying an operationthat caused the error.

Example Computing Device

The techniques described herein can be applied to any device or set ofdevices (machines) capable of running programs and processes. It can beunderstood, therefore, that personal computers, laptops, handheld,portable and other computing devices and computing objects of all kindsincluding cell phones, tablet/slate computers, gaming/entertainmentconsoles and the like are contemplated for use in connection withvarious implementations including those exemplified herein. Accordingly,the general purpose computing mechanism described below in FIG. 11 isbut one example of a computing device.

Implementations can partly be implemented via an operating system, foruse by a developer of services for a device or object, and/or includedwithin application software that operates to perform one or morefunctional aspects of the various implementations described herein.Software may be described in the general context of computer executableinstructions, such as program modules, being executed by one or morecomputers, such as client workstations, servers or other devices. Thoseskilled in the art will appreciate that computer systems have a varietyof configurations and protocols that can be used to communicate data,and thus, no particular configuration or protocol is consideredlimiting.

FIG. 11 thus illustrates an example of a suitable computing systemenvironment 1100 in which one or aspects of the implementationsdescribed herein can be implemented, although as made clear above, thecomputing system environment 1100 is only one example of a suitablecomputing environment and is not intended to suggest any limitation asto scope of use or functionality. In addition, the computing systemenvironment 1100 is not intended to be interpreted as having anydependency relating to any one or combination of components illustratedin the example computing system environment 1100.

With reference to FIG. 11, an example device for implementing one ormore implementations includes a general purpose computing device in theform of a computer 1110. Components of computer 1110 may include, butare not limited to, a processing unit 1120, a system memory 1130, and asystem bus 1122 that couples various system components including thesystem memory to the processing unit 1120.

Computer 1110 typically includes a variety of machine (e.g., computer)readable media and can be any available media that can be accessed by amachine such as the computer 1110. The system memory 1130 may includecomputer storage media in the form of volatile and/or nonvolatile memorysuch as read only memory (ROM) and/or random access memory (RAM), andhard drive media, optical storage media, flash media, and so forth. Byway of example, and not limitation, system memory 1130 may also includean operating system, application programs, other program modules, andprogram data.

A user can enter commands and information into the computer 1110 throughone or more input devices 1140. A monitor or other type of displaydevice is also connected to the system bus 1122 via an interface, suchas output interface 1150. In addition to a monitor, computers can alsoinclude other peripheral output devices such as speakers and a printer,which may be connected through output interface 1150.

The computer 1110 may operate in a networked or distributed environmentusing logical connections to one or more other remote computers, such asremote computer 1170. The remote computer 1170 may be a personalcomputer, a server, a router, a network PC, a peer device or othercommon network node, or any other remote media consumption ortransmission device, and may include any or all of the elementsdescribed above relative to the computer 1110. The logical connectionsdepicted in FIG. 11 include a network 1172, such as a local area network(LAN) or a wide area network (WAN), but may also include othernetworks/buses. Such networking environments are commonplace in homes,offices, enterprise-wide computer networks, intranets and the Internet.

As mentioned above, while example implementations have been described inconnection with various computing devices and network architectures, theunderlying concepts may be applied to any network system and anycomputing device or system in which it is desirable to implement suchtechnology.

Also, there are multiple ways to implement the same or similarfunctionality, e.g., an appropriate API, tool kit, driver code,operating system, control, standalone or downloadable software object,etc., which enables applications and services to take advantage of thetechniques provided herein. Thus, implementations herein arecontemplated from the standpoint of an API (or other software object),as well as from a software or hardware object that implements one ormore implementations as described herein. Thus, various implementationsdescribed herein can have aspects that are wholly in hardware, partly inhardware and partly in software, as well as wholly in software.

The word “example” is used herein to mean serving as an example,instance, or illustration. For the avoidance of doubt, the subjectmatter disclosed herein is not limited by such examples. In addition,any aspect or design described herein as “example” is not necessarily tobe construed as preferred or advantageous over other aspects or designs,nor is it meant to preclude equivalent example structures and techniquesknown to those of ordinary skill in the art. Furthermore, to the extentthat the terms “includes,” “has,” “contains,” and other similar wordsare used, for the avoidance of doubt, such terms are intended to beinclusive in a manner similar to the term “comprising” as an opentransition word without precluding any additional or other elements whenemployed in a claim.

As mentioned, the various techniques described herein may be implementedin connection with hardware or software or, where appropriate, with acombination of both. As used herein, the terms “component,” “module,”“system” and the like are likewise intended to refer to acomputer-related entity, either hardware, a combination of hardware andsoftware, software, or software in execution. For example, a componentmay be, but is not limited to being, a process running on a processor, aprocessor, an object, an executable, a thread of execution, a program,and/or a computer. By way of illustration, both an application runningon a computer and the computer can be a component. One or morecomponents may reside within a process and/or thread of execution and acomponent may be localized on one computer and/or distributed betweentwo or more computers.

The aforementioned systems have been described with respect tointeraction between several components. It can be appreciated that suchsystems and components can include those components or specifiedsub-components, some of the specified components or sub-components,and/or additional components, and according to various permutations andcombinations of the foregoing. Sub-components can also be implemented ascomponents communicatively coupled to other components rather thanincluded within parent components (hierarchical). Additionally, it canbe noted that one or more components may be combined into a singlecomponent providing aggregate functionality or divided into severalseparate sub-components, and that any one or more middle layers, such asa management layer, may be provided to communicatively couple to suchsub-components in order to provide integrated functionality. Anycomponents described herein may also interact with one or more othercomponents not specifically described herein but generally known bythose of skill in the art.

In view of the example systems described herein, methodologies that maybe implemented in accordance with the described subject matter can alsobe appreciated with reference to the flowcharts/flow diagrams of thevarious figures. While for purposes of simplicity of explanation, themethodologies are shown and described as a series of blocks, it is to beunderstood and appreciated that the various implementations are notlimited by the order of the blocks, as some blocks may occur indifferent orders and/or concurrently with other blocks from what isdepicted and described herein. Where non-sequential, or branched, flowis illustrated via flowcharts/flow diagrams, it can be appreciated thatvarious other branches, flow paths, and orders of the blocks, may beimplemented which achieve the same or a similar result. Moreover, someillustrated blocks are optional in implementing the methodologiesdescribed herein.

CONCLUSION

While the invention is susceptible to various modifications andalternative constructions, certain illustrated implementations thereofare shown in the drawings and have been described above in detail. Itshould be understood, however, that there is no intention to limit theinvention to the specific forms disclosed, but on the contrary, theintention is to cover all modifications, alternative constructions, andequivalents falling within the spirit and scope of the invention.

In addition to the various implementations described herein, it is to beunderstood that other similar implementations can be used ormodifications and additions can be made to the describedimplementation(s) for performing the same or equivalent function of thecorresponding implementation(s) without deviating therefrom. Stillfurther, multiple processing chips or multiple devices can share theperformance of one or more functions described herein, and similarly,storage can be effected across a plurality of devices. Accordingly, theinvention is not to be limited to any single implementation, but ratheris to be construed in breadth, spirit and scope in accordance with theappended claims.

What is claimed is:
 1. A system comprising: wrapping code coupled to anerror handler of a routine, in which the routine produces an error andthe wrapping code wraps the error with relevant information to provide awrapped exception instance, including to use an exception type hierarchyto preserve information in the wrapped exception instance including anexception type, and wherein the wrapped exception instance comprises asingle exception instance transformed from a series of errors; and anexception manager that receives the wrapped exception instance anddetermines one or more actions to take based upon the exception type ofthe wrapped exception instance.
 2. The system of claim 1 wherein thewrapped exception type is derived from a higher-level exception type inthe exception type hierarchy.
 3. The system of claim 1 wherein theexception manager takes the one or more actions, including to present aninteractive dialog associated with the exception type.
 4. The system ofclaim 3 wherein the exception manager accesses an exception type tablethat associates exception types with dialogs to select the interactivedialog for the exception type.
 5. The system of claim 3 wherein thedialog includes an interactive input mechanism, which when selected,results in the exception manager taking further action to navigate to alocation in a program that contains the routine, in which the locationis determined based upon information in the wrapped exception type. 6.The system of claim 3 wherein the exception manager accesses anexception type table that associates exception types with dialogs toselect the interactive dialog for the exception type.
 7. The system ofclaim 3 wherein the dialog includes an interactive input mechanism,which when selected, results in the exception manager taking furtheraction to navigate to a location in a program that contains the routine,in which the location is determined based upon information in thewrapped exception type.
 8. The system of claim 1 further comprising alogging mechanism that logs data corresponding to the wrapped exceptioninstance.
 9. The system of claim 1 wherein the wrapping code isconfigured to determine if the error corresponds to a native error, andif so, to create a new exception instance and preserve at least someavailable data associated with the native error, if any, in the newexception instance.
 10. The system of claim 1 wherein the wrapping codeis called with a calling exception type, and wherein the wrapping codedetermines if the calling exception type is an ancestor type of a passedexception instance type, and if so, to preserve the passed exceptioninstance as the wrapped exception instance, and if not, to create a newexception instance corresponding to the calling exception type.
 11. Thesystem of claim 10 wherein the wrapping code creates a new exceptioninstance type, and wherein the wrapping code is further configured topreserve at least some data of the passed exception instance type in thenew exception instance type.
 12. The system of claim 10 wherein thewrapping code creates a new exception instance type, and wherein thewrapping code is further configured to preserve at least some data ofthe passed exception instance type in the new exception instance type.13. The system of claim 1 wherein the wrapped exception instancecorresponds to one link in an asynchronous callback chain.
 14. Thesystem of claim 1 wherein the wrapped exception type is derived from ahigher-level exception type in the exception type hierarchy.
 15. Thesystem of claim 1 wherein the exception manager takes the one or moreactions, including to present an interactive dialog associated with theexception type.
 16. The system of claim 1 further comprising a loggingmechanism that logs data corresponding to the wrapped exceptioninstance.
 17. The system of claim 1 wherein the wrapping code isconfigured to determine if the error corresponds to a native error, andif so, to create a new exception instance and preserve at least someavailable data associated with the native error, if any, in the newexception instance.
 18. The system of claim 1 wherein the wrapping codeis called with a calling exception type, and wherein the wrapping codedetermines if the calling exception type is an ancestor type of a passedexception instance type, and if so, to preserve the passed exceptioninstance as the wrapped exception instance, and if not, to create a newexception instance corresponding to the calling exception type.
 19. Thesystem of claim 1 wherein the wrapped exception instance comprises asingle exception instance transformed from a series of errors.
 20. Asystem comprising: wrapping code coupled to an error handler of aroutine, in which the routine produces an error and the wrapping codewraps the error with relevant information to provide a wrapped exceptioninstance, including to use an exception type hierarchy to preserveinformation in the wrapped exception instance including an exceptiontype, and wherein the wrapped exception instance corresponds to one linkin an asynchronous callback chain; and an exception manager thatreceives the wrapped exception instance and determines one or moreactions to take based upon the exception type of the wrapped exceptioninstance.